How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated at the edge of transmission just above the flywheel gear. It transmits a signal to the ECU via the grey wire (T55/49) and then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The grey wire is located at the edges of the transmission, directly above the flywheel ring. The sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer located in the instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors in the right way.
If this sensor fails, the ECU will display an error code P00160. This indicates that the Crank Shaft is not in line with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit challenging as there are two different connector pins and they perform different functions but the most effective method of testing it is to measure resistance between the sensor and the ECU. When the sensor is operational, it should read around 1000 ohms. If you're having issues with this part, check for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at a high speed, i noticed a huge reduction in power. It was like the engine was running out of gas. Or my injectors weren't firing. I pulled out the spark plugs this morning, three were drenched in gasoline and the fourth was unclean. When I crank the engine without sparks i put tissue on top of each injector hole and the 3 that were drenched in gazoline leap out, however the 4th stays closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I got zero Ohm. So i assume the problem is somewhere else.
I also tried to reset PID without success. The car will start when the G28 is disconnected, but it works fine when the G28 plugged in. However the intermittent misfire issue continues to occur at higher RPM. The website coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not sure what to do, but i feel i have pretty much completely ruled out all other possibilities. But i'm worried that i might have missed something. Please let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both are used in the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or in a local parts store. It is simple to test them: simply switch your DMM into resistance mode audi replacement key and test the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They should be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines needs to know both the position and speed the crankshaft to determine timing of the fuel injector, etc. It utilizes a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either one of these, the diagnostic scanner will display codes that could lead to check here an engine audi convenience key shutdown.
A failing G28 sensor could result in an inaccurate speed counter for your gearbox or a gearbox that shifts faster than normal, or a misfire while in gear. If you are experiencing any of these issues it is most likely that your sensor is failing and requires replacement. The good news is they get more info are very affordable and easily accessible, especially when you're looking at an Bosch model, which is what ours are. Alternately, GM's version this component is an excellent choice.
5. Tachometer
A malfunctioning engine speed sensor could be the reason behind a slew of issues in your vehicle. It's a crucial component of the transmission in your Audi because it relays information to the ECU regarding how fast or slowly the engine is spinning. If the sensor fails, it could disrupt the performance of the transmission, as well as the rest of the car's components.
The G5 engine sensor is located near the edge of the transmission, just above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig, and boost, and also transmitting it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. It should show approximately 1000 ohms of resistance between those two pins. This is a common component across the Audi 80 100, 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.